PCR for specific detection of H7 flagellar variant of fliC among extraintestinal pathogenic Escherichia coli

A newly developed PCR-based assay for the H7 variant of the Escherichia coli flagellin gene, fliC, was 100% sensitive and specific in comparison with serology and probe hybridization. It revealed broad conservation of the H7 fliC variant among phylogenetically diverse lineages of extraintestinal pathogenic E. coli (ExPEC) and superseded serotyping for certain isolates with ambiguous or non-H7 serotyping results. The H7 primers functioned well when incorporated into a multiplex PCR assay for diverse virulence-associated genes of ExPEC.